Well I finally beat the game and now I want to fight the Vanitas Lingering Sediment ,but every time I go to fight him he beats me with one hit. I can dodge all of his attacks ,but I can't find an opening . But I See that Tornadoe does a lot of damage on him

there is a fast way glide behind a rock (or cartweel or slide) and spam strike raid

Sediment- a naturally-occurring material that is broken down by processes of weathering and erosion and is subsequently transported by the action of fluids such as wind, water, or ice, and/or by the force of gravity acting on the particle itself.

 

You must mean Sentiment , anyways, I'm sorry but as I don't have the game, I can't suggest a strategy to use against him, all I can say is don't use any Cure based magic, as Vanitas' Sentiment will copy that, so use potions of any sort instead.

Vanish is very helpful against VS. I personally beat him with only my keyblade, but it gets a bit hard. You just have to wait for openings. 2 easy ones are right after he does that dark spike move and when he's using his shotlock.

You'll see the openings eventually. It took me 100's of go's, but now I can identify opportunities easily ^^

Strike raid method(Hide behinda a pillar and spam strike raid) or the mine attack method(wait till he does a long attack like popping out of the ground, doing that blue ray, or having black screens and spikes appear then drop mines at those moments and stay around the mines so that when he trys to attack you he gets hit) but which ever you go with only use pots dont use cures or curagas and healing magic(he'll copy you if u do)[/align]

for terra i used only my keyblade, with ven i used tornados and aqua i havent done yet

tornado didnt do anything for me use thunder surge and fire surge and a sonic blade make shore to uses that one the second the battle begins works well and dont have any cure magic if u use it so will vanitus bring hipotions and that instead thats for ven

do you have second chance and once more also hide behind the big rock and use torenado

How do I get second chance?

to get the second chance is to melding the;

blizzara + blizzara + pulsing crystal

Vanish is very helpful against VS. I personally beat him with only my keyblade, but it gets a bit hard. You just have to wait for openings. 2 easy ones are right after he does that dark spike move and when he's using his shotlock.

You'll see the openings eventually. It took me 100's of go's, but now I can identify opportunities easily ^^

 

I am soooo using vanish btw wat lv were you?

Obtain Second Chance, Once More, and Tornado. Also increase your HP as much as you can.

As stated, if you plan on surviving one attack, you need Second Chance and Once More. Now with Terra, I have yet to beat him, but seeing as Terra's magic sucks, you probably need to rely on strength, such as Sonic Raid. With Aqua, mines. Crazy mines. And Ven, mines then Tornado when he's in the air, but only if you're close.